1. Field of the Invention
This invention relates to projected video display systems as well as interactive video cursor position indicators, such as light pen systems.
2. Description of the Prior Art
Video display systems, such as the video monitors associated with conventional microcomputers, utilize video cursors (or other position designators) to indicate a designated location on the video display. Typical video cursors are blinking underlines or boxes used with text displays, or arrowheads used with graphic displays. The cursor is moved by the computer user to designate the display locations to be affected by application software. A common application is a video cursor used with word processing software to indicate the location on the display for the next letter to be typed. The user moves the cursor to select the next location.
Desired cursor motion is controlled by user actuation or movement of manual devices such as the computer keyboard, a mouse or trackball. Light pens are used to indicate desired location of cursors by interaction with the video display. That is, the light pen is positioned against the display to detect changes in the light pattern of the display where the pen is positioned. The pen is connected to the computer or other device which creates the display. The computer determines where the light pen is positioned by comparing the timing of the light detected and the light displayed. The computer may then change the video display by regenerating the cursor in the position indicated by the light pen.
Light pens have proven to be useful tools for interaction with video displays, but are limited to applications involving a small number of users at a time because the pen detector must be positioned against the display screen for interaction and the limited size of the monitors. As larger video monitors become available, more users can interact with the same monitor and light pen system at the same time. However, interaction is still limited to the relatively small number of users that can crowd around the video display.
Projected image video displays are becoming available for use by larger groups of users. In a meeting of six to ten users, for example, it would be inconvenient to directly use a typical video monitor as a visual display aid for the meeting. The same display, however, may be projected enlarged on a projection screen and viewed conveniently by the group.
Video display projectors are available in which the information provided to the normal video display is provided in parallel to a special purpose device which recreates an enlarged image by projection on a projection screen.
Projected video display systems are limited in that interaction with the video display must be accomplished directly with the original video display. That is, in a group meeting viewing a projected video display, one group member typically interacts with the original video display while other group members view, but are unable to directly interact with, the projected display. This reduces some of the benefits, particularly the spontaneity, of such video displays.